It is well known that some aquatic lifeforms such as coral and algae grow better when they are subjected to an intermittent flow of water. This intermittent flow of water is known as surge and is representative of the random ebb and flow of water in the natural environment such as a coral reef or water tumbling over a rock in a stream. Another advantage of surge is the introduction of both oxygen and CO2 into the water and maintenance of those levels for healthy growth of aquatic lifeforms. The former is required for respiration of many lifeforms and the second establishes an equilibrium between the atmospheric CO2 and its partial pressure in the water. CO2 is reactive with water in that it produces carbonic acid which establishes a chemical equilibrium with the carbonates to produce a desirable pH. A lack of sufficient air/water exchange in a marine aquarium can lead to an environmental imbalance which is detrimental to the health of lifeforms in the aquarium.
Apparatus exist for creating this surge. One apparatus (U.S. Pat. No. 4,966,096) is the rotatable asymmetric “dump bucket” which is a container usually placed above an aquarium and shaped and configured such that as it is filled with water, the center of gravity shifts from one side of the axis of rotation to a second side of the axis of rotation. When the center of gravity is displaced in this manner, it causes a sudden rotation of the dump bucket further moving the center of gravity to the unstable side and thereby causing the dump bucket to release its contents with high velocity into the aquarium. This sudden dumping of water into the aquarium causes a large, rapid movement of water in the aquarium which mimics the surge of normal ocean water movement as well as produces desirable aeration of the water.
A second apparatus for producing a surge of water in an aquarium is to have an external tank which has a siphon arrangement (U.S. Pat. No. 5,738,137) and a fill rate sufficient to cause a siphon action to start through a large diameter pipe which empties the external tank faster than the inflow can supply fluid. When the level in the tank drops below the inflow level of the siphon, the siphon action is broken and the external tank starts to fill again.
A third apparatus for producing surge is to utilize an external tank whose outlet is obstructed by a flapper (such as that which is used in a flush toilet) to which a float is attached. When the water level reaches a threshold, the buoyant forces on the flapper valve suddenly cause it to rise and release the water in the external tank. This release of water into the aquarium causes a surge.
All three of these well known methods have a significant disadvantage and that disadvantage is the method by which the water is pumped from the aquarium into the external tank. The normal method is to use an impeller pump. Impeller pumps kill all or selectively kill some types of microorganisms (plankton) which are a typical food of some aquatic lifeforms.
There are at least two means for pumping water which do not have the disadvantage of killing plankton and these are air-lift pumps (U.S. Pat. Nos. 3,672,790, 4,035,298, 6,857,392, 4,060,574) and the Archimedes screw, however they are both inefficient at moving fluids.
Surge has also been generated (U.S. Pat. No. 5,732,657) by using compressed air to cause water to flow at a reduced rate from a submerged chamber. The electronic actuation of an air valve through a large air orifice exit port allows the pressurized air to rapidly escape, thereby allowing the displaced water to rapidly return to the submerged chamber. This rapid refilling of the chamber creates a surge. The disadvantage of this method of creating surge is that it requires a volume of air equal to the volume of water to be initially displaced in the surge. It also requires sensing circuitry and an electrically actuated valve. It has the further disadvantage of not aerating the water while performing its function and requiring high pressure compressed air.
Another method of making waves on the surface but which could be adapted for underwater generation of surges (U.S. Pat. No. 4,170,898) is the use of mechanical motor driven wave makers. This method does not aerate the water but only causes water motion and requires large mechanical forces and a great expenditure of energy.
What is needed is in an aquarium environment is an apparatus for creating surge while minimizing the required power, eliminating control circuitry, minimizing the detrimental effects on microfauna life, and increasing air and sea surface gas exchange.
What is needed in hazardous pumping environments is an apparatus for moving non-solid materials utilizing forces which do not cause the non-solid material to become unstable.